1. Field of the Invention
The present invention relates to a method of controlling a message overload on a program in a large capacity electronic switching system controlled by a plurality of processors, and more particularly, to a method of controlling a message overload before a resource is requested for an operating program by the program receiving the plurality of messages.
2. Description of the Related Art
In general, functions of an electronic switching system are performed according to plural programs of a multiprocessor. Accordingly, an operating resource may be monopolized by a specific program of the plural programs and therefore, a message overload may be generated.
In a telecommunication system, such as a telephone system, a switching network is connected between plural subscribers through plural subscriber connection processors. The switching network is also connected between plural processors which analyze calls from the subscribers and process the calls or connect the calls to additional service devices. If one of the processors receives a plurality of function requests simultaneously from plural subscribers, a system fault due to an overload on the processor receiving the function requests may be generated.
Overloads are known in the art and have been handled by a number of different methods. One such method contemplates rerouting a call when an overload is detected, such as described by Daniel C. Kerrigan, et al., in U.S. Pat. No. 5,291,552 entitled Distribution of Calls Among Automatic Call Distributers of a Single Large Customer, and by Mary R. Otto in U.S. Pat. No. 5,299,259 entitled Distributing Calls Over Serving Centers of a Large Customer. A problem is incurred when a call can not be rerouted and, as such, the call is lost.
Another method is discussed by Robert Stockdale in U.S. Pat. No. 4,511,762 entitled Overload Detection and Control System for a Telecommunications Exchange wherein detection of system overload is based upon the time for a central processor to send a responsive message to a line/trunk group, and management of this overload is accomplished by the line/trunk group changing between operational levels in response to the measured time.
A further method includes a counter counting steps and comparing a counted value with a threshold value. Such a method is disclosed by: Robert H. Tickner, et al. in U.S. Pat. No. 5,313,5884 entitled Multiple I/O Processor System; Frans van del Dool in U.S. Pat. No. 5,007,043 entitled Method for Transmitting, Via a Plurality of Asynchronously Time-Divided Transmission Channels, a Flow of Data Cells, the State of a Counter Being Kept Up To Date in Accordance With the Number of Data Cells Per Unit of Time; Georg Daisenberger in U.S. Pat. No. 4,626,625 entitled Telecommunications System, Particularly a Telephone Exchange System, Having Overload Protected Sequential Logic Systems; Gerhafd Wegmann in U.S. Pat. No. 4,658,098 entitled Circuit Arrangement for Telecommunications Switching Systems, Particulaly Telephone Switching systtems, Comprising Information-Processing Central Switch Devices and Sub-Central Switching Facilities Which Supply the Same With Information; and Philip M. Williams in U.S. Pat. No. 5,450,483 entitled Method of Controlling Overloads in a Telecommunications Network.